Total joint replacement (TJR) (also called primary total joint arthroplasty) is a surgical procedure in which the articulating surfaces of a joint are replaced with prosthetic components, or implants. It is a successful procedure, especially for hips, knees, shoulders, and ankles and allows people to restore functionality while greatly reducing pain associated with osteoarthritis.
Bone is a living tissue that is constantly changing through the resorption of matrix by osteoclasts and the deposition of new matrix by osteoblasts. Articular cartilage is an avascular tissue that is found on the surfaces of joints and serves to provide a smooth interface upon which bones can articulate with each other. Joint replacement arthroplasty is an orthopedic procedure in which the typically worn surface of the joint is replaced with a prosthetic component, or implant. Joint replacement arthroplasty typically requires the removal of the articulating cartilage surface of the joint including a varying amount of bone depending on the joint and the replacement implant being used. This cartilage and bone is then replaced with a synthetic, typically metal implant that is used to create a new joint surface.
The replacement implants used in joint replacement surgeries have a limited life expectancy and will often need to be replaced. Replacement of a joint replacement implant is called revision total joint replacement (RTJR) and involves removing the old implant(s) from the bone, removing any bone cement (polymethylmethacrylate or PMMA) used during the TJR, reshaping the bone to fit new revision implant(s), and placing the new revision implant(s) into the bone. RTJR is known to be a difficult and lengthy procedure because the surgeon typically has a limited amount of information about the location and amount of bone cement from the previous TJR. Removal of both the old implant and the bone cement is typically performed using a variety of hand tools including osteotomes, saws, punches, power saws, power burs, and ultrasonic instruments. However, these tools can be tedious to use especially when trying to remove bone cement from deeper cavities or small holes. Additionally, these tools present a risk of fracturing the bone when removing the implant or the bone cement. To increase visibility of the bone cement and bone-implant interface, holes or windows may be cut or drilled into the bone. However, this may weaken the bone and increase the risk of later fracture.
Revision joint arthroplasty is a technically difficult procedure that often presents intraoperative challenges. For example, difficulties in removing the previous implant or the bone cement may result in an excess removal of healthy bone. Additionally, the bone structure may be damaged from the tools and the length of time required to adequately remove all of the bone cement, may put the patient's safety at risk. A computer implemented system and method for removing bone cement or other material is described in U.S. Pat. No. 5,769,092 assigned to the assignee of the present application. However, there have been advances in imaging which may allow for an improved removal of bone and or bone cement during a revision joint arthroplasty. Thus, there exists a need for a more effective process to adequately remove the previous implant, any bone cement, and prepare a new cavity for a revision implant without further compromising the structure of the bone.